You are getting , as usual for this subject, a lot of biased advice much of which is based on myth, ignorance, anecdotal evidence and other hokum.
All of these comments about speed are just off the mark. ST tires like all others have speed ratings. I have never seen verifiable evidence of a purely speed related blowout.
Heat is generated by under-inflation. This is without doubt the most common cause of blowouts, followed by delamination of the steel belts for reasons of mfg defects or puncture.
There is NOTHING inherently bad about ST tires. This is the worst myth of all. ST tires are used on all tractor trailer combination vehicle trailers and go hundreds of thousands of miles before changing in many cases. The same technology or more properly design elements are in your small ST tires as are in the full size 22.5 St tires. They are made and designed specifically for the work they do.
ST tires have increased sidewall stiffness and strength to resist the sideways scuffing they get during turns. The must have less flex than car or truck tires (this helps the trailer track better and wallow less)
And like many topics on this site this one too is often over analyzed, over thought and mountains are made of molehills. Keep your tires properly inflated. That is the ONE THING you can do more than anything that makes a difference.
I check my inflation with a gauge before I start from home or campground everytime. COLD. I inflate to the Maximum cold inflation marked on the tire. I also walk around my entire rig every time I stop for fuel or any other reason and one of the points I check is a visual on all the tires and wheels.
Blowouts happen. They always have and probably always will. But they are much much much less common then they were years ago. And they happen to ANY TIRE no matter it's origin or manufacturer.